Endoscopic procedures for treating abnormal pathologies within the alimentary canal system and biliary tree (including the biliary, hepatic, and pancreatic ducts) are increasing in number. The endoscope provides access to the general area of a desired duct using direct visualization. However, the duct itself must be navigated using a catheter in conjunction with a guidewire under fluoroscopy. A wide variety of catheters are known for treatment of such targeted anatomical regions. Examples of biliary catheters are disclosed in U.S. Pat. No. 5,397,302 to Weaver et al., U.S. Pat. No. 5,320,602 to Karpiel and U.S. Pat. No. 5,921,971 to Argo et al., the disclosures of which are hereby incorporated by reference.
Argo et al. '971 discloses a catheter for use in biliary procedures, wherein the catheter includes a shaft having a proximal end and a distal end. A guidewire lumen extends through the shaft from a proximal guidewire port located proximal of the distal end of the shaft, to a distal guidewire port located at the distal end of the shaft. The shaft may also include a slot or channel extending from a proximal end of the shaft to the proximal guidewire port. By utilizing a slot or channel, the proximal shaft portion has a non-circular profile or cross-section as best seen in FIGS. 5A and 6A of Argo et al. '971. Catheters incorporating such a guidewire opening and channel are often referred to as rapid exchange or single operator exchange type biliary catheters. One drawback with such rapid exchange or single operator exchange biliary catheters is the inability or relative difficulty in sealing around the non-circular shaft, such that fluid (bile liquid and air) may leak out of the working channel of the endoscope around the non-circular shaft of the biliary catheter.
Conventional endoscope seals are adapted to seal about catheters having circular shafts, and generally do not effectively seal about catheters having non-circular shafts. Such conventional seals are commercially available from Olympus, Fuji and Pentax. An example of a prior art endoscope seal is disclosed in U.S. Pat. No. 4,920,953 to McGown. The endoscope seals commercially available and the endoscope seal disclosed in McGown '953 generally include a body portion having a proximal end adapted to receive an elongate device such as a biliary catheter, a distal end adapted for connection to the proximal end of the endoscope, a lumen extending through the body portion, and a membrane disposed in the lumen, wherein the membrane includes a small circular hole or aperture. The circular aperture is sized to closely fit the elongate device inserted therein such that fluids (bile and air) do not readily escape from the working channel of the endoscope.
However, it can be readily appreciated that when a biliary catheter or other elongate device having a shaft with a non-circular cross section is placed through the circular aperture, at least a portion of the aperture does not engage the non-circular shaft. Accordingly, such prior art endoscope seals do not effectively inhibit the egress of bile liquids and air exiting the working channel of the endoscope when an elongate device having a non-circular cross-section is utilized. Because rapid exchange catheters are becoming more prevalent, and because such rapid exchange catheters have a non-circular shaft cross-section, there is a significant demand for an endoscope seal that effectively seals or inhibits the egress of fluid from the working channel of an endoscope, when a device having a non-circular shaft cross-section is used therewith.